A point-to-multi-point passive optical network (PON) operates as a communication system by broadcasting optical signals downstream from a central unit, herein termed an optical line termination (OLT), to optical network terminations (ONTs). The signals are transferred from the OLT to the ONTs via fibre optic cables and passive optical splitters, which comprise the physical fabric of the network. For upstream communication, each ONT must be able to transmit signals which are not interfered with by other ONTs.
One of the methods known in the art for performing such upstream and downstream transmissions is by using time division multiple access (TDMA), wherein each ONT is allocated a window when only it can transmit, and where the OLT also has windows for transmission to specific ONTs. Other methods for avoiding interference include transmitting signals at different wavelengths, using wavelength division multiple access (WDMA). Combinations of TDMA and WDMA are also known in the art. Signals are typically transmitted within the PON according to an protocol based on these methods. Upstream of the OLT, signals are typically transferred via an industry-standard data transmission protocol, such as an Ethernet protocol.
As demand on transmission networks increases, the need for improving the flexibility of the networks also increases. One way in which network flexibility may be increased is by enabling elements of the network to convey data via more than one protocol.